This invention relates to a carrier in a circular knitting machine for mounting parts of a group of parts including at least needles, sinkers and cam parts, which carrier has at least one flow channel intended for the transport of a gaseous or fluid medium and comprising a recess formed in and adjoining a surface of the carrier.
In the operation of high performance knitting machines with large numbers of systems and speeds of rotation, especially large circular knitting machines with large diameters of e.g. 30", high frictional forces arise, which have their origin in the movements of the knitting implements (needles, jacks, sinkers or the like) relative to the carriers receiving the same (needle cylinder, dial, sinker ring or the like), or the cam parts controlling them, fixed to further carriers. These frictional forces do not only result in rapid wear of the rubbing partners and a high energy requirement for the circular knitting machine but also lead to such severe heating up to e.g. about 150.degree. C. that the said parts can no longer be handled and necessary repairs, e.g. changing a broken needle, are only possible with special safety precautions or after adequate cooling of the circular knitting machine.
Apart from this, in circular knitting machines which run hot disturbances to operation, e.g. pattern errors or changes in the loop lengths or the yarn tension, which do not arise with cold or slow running machines, are frequently observed, even when the circular knitting machine is optimally adjusted at room temperature. These disturbances to operation must therefore be attributed to temperature effects, so that changing operating temperatures have an unfavourable influence on the functional reliability of a circular knitting machine. Finally it is known that circular knitting machines can tend to malfunction even on cold starting and that it can therefore be advantageous initially to allow them to warm up at a slow speed of rotation, before they are switched to the rated speed.
The sole possibility for providing effective relief has hitherto been the use of lubricating and/or heat exchange devices. These can for example comprise blowing or spray nozzles, by means of which gaseous heat exchange media, especially air, or fluid lubricants, especially oil, are blown or sprayed from the outside or the inside on to the knitting implements, their carriers and/or the cam arrangements, or heat exchange or lubricating circuits formed in the carriers, through which a fluid heat exchange or lubricating medium, especially water or oil, is fed. In an earlier proposal of the same applicants it has already been suggested to provide a heat exchange with at least two circuits for a fluid heat exchange medium, where the one circuit is associated with the carrier and the other circuit with the cam arrangement, in order thereby to moderate the temperature of the carrier and the cam arrangement in a controlled manner with their own associated circuits and so to control the heat exchange rate of at least one circuit in such a manner that substantially the same temperature difference between the carrier and the cam arrangement is established under all operating conditions of the circular knitting machine.
The technical realisation of such lubricating and/or heat exchange devices has however been deficient hitherto. A significant reason for this lies above all in that the formation of the heat exchange or lubricating channels in the carrier cannot be made sufficiently effective. These channels consist either of hose lines laid into channel-like recesses in the carrier (DE-OS 2 200 154), which do not make for a completely satisfactory heat exchange, or of channels and bores open on several sides (DE-OS 1 635 836) suited only to the use of air as heat exchange medium. Alternatively, open collecting channels are indeed known, which lead the heat exchange or lubricating medium to selected bores, from whence it is transported to a location provided for the heat exchange or lubrication (DE-PS 1 635 931), but such collecting channels are not always desirable on account of the sealing problems and on account of the high energy loss with necessary heating of the carrier.